Shielding with display elements

ABSTRACT

A method and apparatus for operating an input device having a touch sensor and associated display device is discussed. While performing touch sensing, inactive transmitter electrodes of the touch sensor are electrically floated, and one or more source lines from the display device are operated to achieve shielding against interference, such as that coming from a backlight underneath the touch sensor.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/929,570, filed Jun. 27, 2013 which claims benefit of U.S. ProvisionalPatent application Ser. No. 61/784,135, filed Mar. 14, 2013, which areherein incorporated by reference in their entireties.

FIELD

Embodiments of the present disclosure relate to an input device,processing system, and method for shielding during touch sensing.

BACKGROUND

Input devices including proximity sensor devices (also commonly calledtouchpads or touch sensor devices) are widely used in a variety ofelectronic systems. A proximity sensor device typically includes asensing region, often demarked by a surface, in which the proximitysensor device determines the presence, location and/or motion of one ormore input objects. Proximity sensor devices may be used to provideinterfaces for the electronic system. For example, proximity sensordevices are often used as input devices for larger computing systems(such as opaque touchpads integrated in, or peripheral to, notebook ordesktop computers). Proximity sensor devices are also often used insmaller computing systems (such as touch screens integrated in cellularphones).

SUMMARY OF THE DISCLOSURE

An input device, processing system for an input device, and method foroperating capacitive touch sensors are disclosed herein. In oneembodiment, a display device having a plurality of transmitterelectrodes configured to be driven for capacitive sensing and having afirst transmitter electrode and a second transmitter electrode. Thedisplay device includes a plurality of receiver electrodes and aplurality of conductive electrodes in a thin-film-transistor (TFT) layerof the display device. The display device further includes a processingsystem coupled to the plurality of transmitter electrodes, the pluralityof receiver electrodes. The plurality of conductive electrodes, whereinthe processing system is configured to drive the first transmitterelectrode with a transmitter signal, electrically float the secondtransmitter electrode while driving the first transmitter electrode, andreceive resulting signals with the receiver electrodes, the resultingsignals comprising effects corresponding to the transmitter signal. Theprocessing system is further configured to, while driving the firsttransmitter electrode, at least one of: (i) drive at least one of theplurality of conductive electrodes with a first signal, and (ii)electrically float at least one of the plurality of conductiveelectrodes.

In another embodiment, a processing system for a display device havingan integrated capacitive sensing device includes a driver modulecomprising driver circuitry configured to be coupled to a plurality oftransmitter electrodes having a first transmitter electrode and a secondtransmitter electrode, and to a plurality of conductive electrodes in athin-film-transistor (TFT) layer of the display device. The drivermodule is configured to drive a transmitter signal with the firsttransmitter electrode, while electrically floating the secondtransmitter electrode. The driver module is further configured to, whiledriving the first transmitter electrode, at least one of: (i) drive atleast one of the plurality of conductive electrodes with a first signal,and (ii) electrically float at least one of the plurality of conductiveelectrodes. The processing system further includes a receiver moduleconfigured to be coupled to a plurality of receiver electrodes andconfigured to receive resulting signals with the receiver electrodes,the resulting signals comprising effects corresponding to thetransmitter signal.

In another embodiment, a method for operating a display device having anintegrated capacitive sensing device includes driving a firsttransmitter electrode with a transmitter signal for capacitive sensing.The method further includes electrically floating a second transmitterelectrode while driving the first transmitter electrode. The methodfurther includes, while driving the first transmitter electrode, atleast one of: (i) driving at least one of a plurality of conductiveelectrodes in a thin-film-transistor (TFT) layer of the display devicewith a first signal, and (ii) electrically floating at least one of theplurality of conductive electrodes. The method includes receivingresulting signal from a plurality of receiving electrodes, the resultingsignals comprising effects corresponding to the transmitter signal.

In another embodiment, a display device having an integrated capacitivesensing device includes a plurality of common electrodes configured tobe driven for display updating and capacitive sensing. The plurality ofcommon electrodes includes a first common electrode set corresponding toa first transmitter electrode and a second common electrode setcorresponding to a second electrode. The display device includes athin-film-transistor (TFT) layer having a plurality of conductiveelectrodes, and a plurality of receiver electrodes. The display devicefurther includes a processing system coupled to the plurality of commonelectrodes, the plurality of receiver electrodes, and the plurality ofconductive electrodes. The processing system is configured to drive thefirst transmitter electrode with a transmitter signal, electricallyfloat the second transmitter electrode while driving the firsttransmitter electrode, while driving the first transmitter electrode,drive at least one of the plurality of conductive electrodes to a firstvoltage signal. The processing system is further configured to receiveresulting signals with the receiver electrodes, the resulting signalscomprising effects corresponding to the transmitter signal.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentdisclosure can be understood in detail, a more particular description ofthe disclosure, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlytypical embodiments of this disclosure and are therefore not to beconsidered limiting of its scope, for the disclosure may admit to otherequally effective embodiments.

FIG. 1 is a schematic diagram of an exemplary input device, inaccordance with embodiments of the disclosure.

FIG. 2 illustrates the input device in greater detail, including systemsfor updating pixels in an associated display screen, according to oneembodiment of the disclosure.

FIG. 3 illustrates an alternative embodiment of the input deviceconfigured to shield with display elements.

FIG. 4 is a flow diagram illustrating a method for operating an inputdevice, according to one embodiment of the disclosure.

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures. It is contemplated that elements disclosed in oneembodiment may be beneficially utilized on other embodiments withoutspecific recitation. The drawings referred to here should not beunderstood as being drawn to scale unless specifically noted. Also, thedrawings are often simplified and details or components omitted forclarity of presentation and explanation. The drawings and discussionserve to explain principles discussed below, where like designationsdenote like elements.

DETAILED DESCRIPTION

The following detailed description is merely exemplary in nature and isnot intended to limit the invention or the application and uses of theinvention. Furthermore, there is no intention to be bound by anyexpressed or implied theory presented in the preceding technical field,background, brief summary or the following detailed description.

Embodiments of the present disclosure provide input devices and methodsfor decreasing settling time of the input devices. Input devices mayhave sensor devices that are in close proximity to a display screen,e.g., a cellular phone with a touch-enabled display screen. To operatethe sensor devices to track an input object, the input device may drivea modulated electrical signal onto transmitter electrodes and detect achange in an electrical property (e.g., capacitance) between thetransmitter electrodes and receiver electrodes caused by the inputobject. The input device may use the inactive transmitter electrodes toshield against interference coming from underneath the sensor device(e.g., from a backlight of the display screen) by connecting theinactive transmitter electrodes to an actively driven level. However,using the inactive transmitter electrodes for shielding may have anegative impact on the sensor device in other ways. Specifically, usinginactive transmitter electrodes for shielding may cause the capacitiveload and the settling time of the sensor device to increase. Thisproblem may arise more frequently as input devices become bigger andhave larger sensor devices and larger display screens.

To provide shielding while reducing the settling time of the sensordevice, the input device may use electrodes found within the displayscreen to shield against interference while performing touch sensing. Inone embodiment, the input device may use conductive electrodes, such assource lines, or gate lines, within the thin-film-transistor layer ofthe display screen to shield the sensor device from interference duringtouch sensing. For example, while the sensor device performs touchsensing, the input device may drive the source lines of the displayscreen to a level and electrically float the inactive transmitterelectrodes. This technique may be applied to a number of configurationsof sensor devices, including “on-cell,” “full in-cell”, and “hybridin-cell” sensors, as described below.

FIG. 1 is a block diagram of an exemplary input device 100, inaccordance with embodiments of the present technology. Althoughembodiments of the present disclosure may be utilized in an input device100 including a display device integrated with a sensing device, it iscontemplated that the invention may be embodied in display deviceswithout integrated sensing devices. The input device 100 may beconfigured to provide input to an electronic system 150. As used in thisdocument, the term “electronic system” (or “electronic device”) broadlyrefers to any system capable of electronically processing information.Some non-limiting examples of electronic systems 150 include personalcomputers of all sizes and shapes, such as desktop computers, laptopcomputers, netbook computers, tablets, web browsers, e-book readers, andpersonal digital assistants (PDAs). Additional example electronicsystems 150 include composite input devices, such as physical keyboardsthat include input device 100 and separate joysticks or key switches.Further example electronic systems 150 include peripherals such as datainput devices (including remote controls and mice), and data outputdevices (including display screens and printers). Other examples includeremote terminals, kiosks, and video game machines (e.g., video gameconsoles, portable gaming devices, and the like). Other examples includecommunication devices (including cellular phones, such as smart phones),and media devices (including recorders, editors, and players such astelevisions, set-top boxes, music players, digital photo frames, anddigital cameras). Additionally, the electronic system could be a host ora slave to the input device.

The input device 100 can be implemented as a physical part of theelectronic system 150, or can be physically separate from the electronicsystem 150. As appropriate, the input device 100 may communicate withparts of the electronic system using any one or more of the following:buses, networks, and other wired or wireless interconnections. Examplesinclude I²C, SPI, PS/2, Universal Serial Bus (USB), Bluetooth, RF, andIRDA.

In FIG. 1, the input device 100 is shown as a proximity sensor device(also often referred to as a “touchpad” or a “touch sensor device”)configured to sense input provided by one or more input objects 140 in asensing region 120. Example input objects include fingers and styli, asshown in FIG. 1.

Sensing region 120 encompasses any space above, around, in and/or nearthe input device 100 in which the input device 100 is able to detectuser input (e.g., user input provided by one or more input objects 140).The sizes, shapes, and locations of particular sensing regions may varywidely from embodiment to embodiment. In some embodiments, the sensingregion 120 extends from a surface of the input device 100 in one or moredirections into space until signal-to-noise ratios prevent sufficientlyaccurate object detection. The distance to which this sensing region 120extends in a particular direction, in various embodiments, may be on theorder of less than a millimeter, millimeters, centimeters, or more, andmay vary significantly with the type of sensing technology used and theaccuracy desired. Thus, some embodiments sense input that comprises nocontact with any surfaces of the input device 100, contact with an inputsurface (e.g., a touch surface) of the input device 100, contact with aninput surface of the input device 100 coupled with some amount ofapplied force or pressure, and/or a combination thereof. In variousembodiments, input surfaces may be provided by surfaces of casingswithin which the sensor electrodes reside, by face sheets applied overthe sensor electrodes or any casings, etc. In some embodiments, thesensing region 120 has a rectangular shape when projected onto an inputsurface of the input device 100.

The input device 100 may utilize any combination of sensor componentsand sensing technologies to detect user input in the sensing region 120.The input device 100 comprises one or more sensing elements 121 fordetecting user input. As several non-limiting examples, the input device100 may use capacitive, elastive, resistive, inductive, magnetic,acoustic, ultrasonic, and/or optical techniques.

Some implementations are configured to provide images that span one,two, three, or higher dimensional spaces. Some implementations areconfigured to provide projections of input along particular axes orplanes.

In some resistive implementations of the input device 100, a flexibleand conductive first layer is separated by one or more spacer elementsfrom a conductive second layer. During operation, one or more voltagegradients are created across the layers. Pressing the flexible firstlayer may deflect it sufficiently to create electrical contact betweenthe layers, resulting in voltage outputs reflective of the point(s) ofcontact between the layers. These voltage outputs may be used todetermine positional information.

In some inductive implementations of the input device 100, one or moresensing elements 121 pick up loop currents induced by a resonating coilor pair of coils. Some combination of the magnitude, phase, andfrequency of the currents may then be used to determine positionalinformation.

In some capacitive implementations of the input device 100, voltage orcurrent is applied to one or more capacitive sensing elements 121 tocreate an electric field between an electrode and ground. Nearby inputobjects 140 cause changes in the electric field, and produce detectablechanges in capacitive coupling that may be detected as changes involtage, current, or the like.

Some capacitive implementations utilize arrays or other regular orirregular patterns of capacitive sensing elements 121 to create electricfields. In some capacitive implementations, separate sensing elements121 may be ohmically shorted together to form larger sensor electrodes.Some capacitive implementations utilize resistive sheets, which may beuniformly resistive.

Some capacitive implementations utilize “self capacitance” (or “absolutecapacitance”) sensing methods based on changes in the capacitivecoupling between sensor electrodes and an input object. In variousembodiments, an input object near the sensor electrodes alters theelectric field near the sensor electrodes, thus changing the measuredcapacitive coupling. In one implementation, an absolute capacitancesensing method operates by modulating sensor electrodes with respect toa reference voltage (e.g., system ground), and by detecting thecapacitive coupling between the sensor electrodes and input objects.

Some capacitive implementations utilize “mutual capacitance” (or“transcapacitance”) sensing methods based on changes in the capacitivecoupling between sensor electrodes. In various embodiments, an inputobject near the sensor electrodes alters the electric field between thesensor electrodes, thus changing the measured capacitive coupling. Inone implementation, a transcapacitive sensing method operates bydetecting the capacitive coupling between one or more transmitter sensorelectrodes (also “transmitter electrodes” or “transmitters”) and one ormore receiver sensor electrodes (also “receiver electrodes” or“receivers”). Transmitter sensor electrodes may be modulated relative toa reference voltage (e.g., system ground) to transmit transmittersignals. Receiver sensor electrodes may be held substantially constantrelative to the reference voltage to facilitate receipt of resultingsignals. A resulting signal may comprise effect(s) corresponding to oneor more transmitter signals, and/or to one or more sources ofenvironmental interference (e.g., other electromagnetic signals). Sensorelectrodes may be dedicated transmitters or receivers, or may beconfigured to both transmit and receive.

In FIG. 1, the processing system 110 is shown as part of the inputdevice 100. The processing system 110 is configured to operate thehardware of the input device 100 to detect input in the sensing region120. The processing system 110 comprises parts of or all of one or moreintegrated circuits (ICs) and/or other circuitry components. (Forexample, a processing system for a mutual capacitance sensor device maycomprise transmitter circuitry configured to transmit signals withtransmitter sensor electrodes, and/or receiver circuitry configured toreceive signals with receiver electrodes). In some embodiments, theprocessing system 110 also comprises electronically-readableinstructions, such as firmware code, software code, and/or the like. Insome embodiments, components composing the processing system 110 arelocated together, such as near sensing element(s) of the input device100. In other embodiments, components of processing system 110 arephysically separate with one or more components close to sensingelement(s) of input device 100, and one or more components elsewhere.For example, the input device 100 may be a peripheral coupled to adesktop computer, and the processing system 110 may comprise softwareconfigured to run on a central processing unit of the desktop computerand one or more ICs (perhaps with associated firmware) separate from thecentral processing unit. As another example, the input device 100 may bephysically integrated in a phone, and the processing system 110 maycomprise circuits and firmware that are part of a main processor of thephone. In some embodiments, the processing system 110 is dedicated toimplementing the input device 100. In other embodiments, the processingsystem 110 also performs other functions, such as operating displayscreens, driving haptic actuators, etc.

The processing system 110 may be implemented as a set of modules thathandle different functions of the processing system 110. Each module maycomprise circuitry that is a part of the processing system 110,firmware, software, or a combination thereof. In various embodiments,different combinations of modules may be used. Example modules includehardware operation modules for operating hardware such as sensorelectrodes and display screens, data processing modules for processingdata such as sensor signals and positional information, and reportingmodules for reporting information. Further example modules includesensor operation modules configured to operate sensing element(s) todetect input, identification modules configured to identify gesturessuch as mode changing gestures, and mode changing modules for changingoperation modes.

In some embodiments, the processing system 110 responds to user input(or lack of user input) in the sensing region 120 directly by causingone or more actions. Example actions include changing operation modes,as well as GUI actions such as cursor movement, selection, menunavigation, and other functions. In some embodiments, the processingsystem 110 provides information about the user input (or lack of userinput) to some part of the electronic system (e.g., to a centralprocessing system of the electronic system that is separate from theprocessing system 110, if such a separate central processing systemexists). In some embodiments, some part of the electronic systemprocesses information received from the processing system 110 to act onuser input, such as to facilitate a full range of actions, includingmode changing actions and GUI actions.

For example, in some embodiments, the processing system 110 operates thesensing element(s) of the input device 100 to produce electrical signalsindicative of input (or lack of input) in the sensing region 120. Theprocessing system 110 may perform any appropriate amount of processingon the electrical signals in producing the information provided to theelectronic system. For example, the processing system 110 may digitizeanalog electrical signals obtained from the sensor electrodes. Asanother example, the processing system 110 may perform filtering orother signal conditioning. As yet another example, the processing system110 may subtract or otherwise account for a baseline, such that theinformation reflects a difference between the electrical signals and thebaseline. As yet further examples, the processing system 110 maydetermine positional information, recognize inputs as commands,recognize handwriting, and the like.

“Positional information” as used herein broadly encompasses absoluteposition, relative position, velocity, acceleration, and other types ofspatial information. Exemplary “zero-dimensional” positional informationincludes near/far or contact/no contact information. Exemplary“one-dimensional” positional information includes positions along anaxis. Exemplary “two-dimensional” positional information includesmotions in a plane. Exemplary “three-dimensional” positional informationincludes instantaneous or average velocities in space. Further examplesinclude other representations of spatial information. Historical dataregarding one or more types of positional information may also bedetermined and/or stored, including, for example, historical data thattracks position, motion, or instantaneous velocity over time.

In some embodiments, the input device 100 is implemented with additionalinput components that are operated by the processing system 110 or bysome other processing system. These additional input components mayprovide redundant functionality for input in the sensing region 120, orsome other functionality. FIG. 1 shows buttons 130 near the sensingregion 120 that can be used to facilitate selection of items using theinput device 100. Other types of additional input components includesliders, balls, wheels, switches, and the like. Conversely, in someembodiments, the input device 100 may be implemented with no other inputcomponents.

In some embodiments, the input device 100 comprises a touch screeninterface, and the sensing region 120 overlaps at least part of anactive area of a display screen. For example, the input device 100 maycomprise substantially transparent sensor electrodes overlaying thedisplay screen and provide a touch screen interface for the associatedelectronic system. The display screen may be any type of dynamic displaycapable of displaying a visual interface to a user, and may include anytype of light emitting diode (LED), organic LED (OLED), cathode ray tube(CRT), liquid crystal display (LCD), plasma, electroluminescence (EL),or other display technology. The input device 100 and the display devicemay share physical elements. For example, some embodiments may utilizesome of the same electrical components for displaying and sensing. Asanother example, the display device may be operated in part or in totalby the processing system 110.

It should be understood that while many embodiments of the presenttechnology are described in the context of a fully functioningapparatus, the mechanisms of the present technology are capable of beingdistributed as a program product (e.g., software) in a variety of forms.For example, the mechanisms of the present technology may be implementedand distributed as a software program on information bearing media thatare readable by electronic processors (e.g., non-transitorycomputer-readable and/or recordable/writable information bearing mediareadable by the processing system 110). Additionally, the embodiments ofthe present technology apply equally regardless of the particular typeof medium used to carry out the distribution. Examples ofnon-transitory, electronically readable media include various discs,memory sticks, memory cards, memory modules, and the like.Electronically readable media may be based on flash, optical, magnetic,holographic, or any other storage technology.

FIG. 2 shows in greater detail the input device 100 including an examplepattern of sensing elements 121 configured to sense in a sensing region120 associated with the pattern. For clarity of illustration anddescription, FIG. 2 shows the sensing elements 121 in a pattern ofsimple rectangles, and does not show various components. The sensingelements 121 may have other suitable geometry or form. The illustratedpattern of sensing elements 121 comprises a first plurality of sensorelectrodes 202 (202-1, 202-2, 202-3, . . . 202-n), and a secondplurality of sensor electrodes 204 (204-1, 204-2, 204-3, . . . 204-m)disposed over the first plurality of sensor electrodes 202. In oneembodiment, processing system 110 is coupled to sensor electrodes 202and 204 and is configured to transmit transmitter signals with the firstplurality of sensor electrodes 202 and receive resulting signals withthe second plurality of sensor electrodes 204. In such an embodiment,the first plurality of sensor electrode may be referred to as aplurality of transmitter electrodes 202 (202-1, 202-2, 202-3, . . .202-n), and the second plurality of sensor electrodes may be referred toas a plurality of receiver electrodes 204 (204-1, 204-2, 204-3, . . .204-m). In one embodiment, the plurality of receiver electrodes 204 maybe disposed over the plurality of transmitter electrodes 202. In anotherembodiment, processing system 110 may be configured to transmit andreceive with both the first plurality of sensor electrodes and thesecond plurality of sensor electrodes.

Transmitter electrodes 202 and receiver electrodes 204 are typicallyohmically isolated from each other. That is, one or more insulatorsseparate transmitter electrodes 202 and receiver electrodes 204 andprevent them from electrically shorting to each other. In someembodiments, transmitter electrodes 202 and receiver electrodes 204 areseparated by insulative material disposed between them at cross-overareas; in such constructions, the transmitter electrodes 202 and/orreceiver electrodes 204 may be formed with jumpers connecting differentportions of the same electrode. In some embodiments, transmitterelectrodes 202 and receiver electrodes 204 are separated by one or morelayers of insulative material. In some other embodiments, transmitterelectrodes 202 and receiver electrodes 204 are separated by one or moresubstrates; for example, they may be disposed on opposite sides of thesame substrate, or on different substrates that are laminated together.

The areas of localized capacitive coupling between transmitterelectrodes 202 and receiver electrodes 204 may be termed “capacitivepixels.” The capacitive coupling between the transmitter electrodes 202and receiver electrodes 204 change with the proximity and motion ofinput objects in the sensing region associated with the transmitterelectrodes 202 and receiver electrodes 204.

In some embodiments, the sensor pattern is “scanned” to determine thesecapacitive couplings. That is, the transmitter electrodes 202 are drivento transmit transmitter signals. Transmitters may be operated such thatone transmitter electrode transmits at one time, or multiple transmitterelectrodes transmit at the same time. Where multiple transmitterelectrodes transmit simultaneously, these multiple transmitterelectrodes may transmit the same transmitter signal and effectivelyproduce an effectively larger transmitter electrode, or these multipletransmitter electrodes may transmit different transmitter signals. Forexample, multiple transmitter electrodes may transmit differenttransmitter signals according to one or more coding schemes that enabletheir combined effects on the resulting signals of receiver electrodes204 to be independently determined.

The receiver electrodes 204 may be operated singly or multiply toacquire resulting signals. The resulting signals may be used todetermine measurements of the capacitive couplings at the capacitivepixels.

A set of measurements from the capacitive pixels form a “capacitiveimage” (also “capacitive frame”) representative of the capacitivecouplings at the pixels. Multiple capacitive images may be acquired overmultiple time periods, and differences between them used to deriveinformation about input in the sensing region. For example, successivecapacitive images acquired over successive periods of time can be usedto track the motion(s) of one or more input objects entering, exiting,and within the sensing region.

The background capacitance of a sensor device is the capacitive imageassociated with no input object in the sensing region. The backgroundcapacitance changes with the environment and operating conditions, andmay be estimated in various ways. For example, some embodiments take“baseline images” when no input object is determined to be in thesensing region, and use those baseline images as estimates of theirbackground capacitances.

Capacitive images can be adjusted for the background capacitance of thesensor device for more efficient processing. Some embodiments accomplishthis by “baselining” measurements of the capacitive couplings at thecapacitive pixels to produce a “baselined capacitive image.” That is,some embodiments compare the measurements forming a capacitance imagewith appropriate “baseline values” of a “baseline image” associated withthose pixels, and determine changes from that baseline image.

In some touch screen embodiments, transmitter electrodes 202 compriseone or more common electrodes (e.g., “V-com electrodes” or segments of asegmented V-com electrode) used in updating the display of the displayscreen. These common electrodes may be disposed on an appropriatedisplay screen substrate. For example, the common electrodes may bedisposed on the TFT glass in some display screens (e.g., In PlaneSwitching (IPS) or Plan to Line Switching (PLS)), on the bottom of thecolor filter glass of some display screens (e.g., Patterned VerticalAlignment (PVA) or Multi-domain Vertical Alignment (MVA)), etc. In suchembodiments, the common electrode can also be referred to as a“combination electrode”, since it performs multiple functions. Invarious embodiments, each transmitter electrode 202 comprises one ormore common electrodes. In other embodiments, at least two transmitterelectrodes 202 may share at least one common electrode. An exampleembodiment having transmitter electrodes 202 that comprise one or morecommon electrodes 212 is discussed later in conjunction with FIG. 3.

In various touch screen embodiments, the “capacitive frame rate” (therate at which successive capacitive images are acquired) may be the sameor be different from that of the “display frame rate” (the rate at whichthe display image is updated, including refreshing the screen toredisplay the same image). In some embodiments where the two ratesdiffer, successive capacitive images are acquired at different displayupdating states, and the different display updating states may affectthe capacitive images that are acquired. That is, display updatingaffects, in particular, the background capacitive image. Thus, if afirst capacitive image is acquired when the display updating is at afirst state, and a second capacitive image is acquired when the displayupdating is at a second state, the first and second capacitive imagesmay differ due to differences in the background capacitive imageassociated with the display updating states, and not due to changes inthe sensing region. This is more likely where the capacitive sensing anddisplay updating electrodes are in close proximity to each other, orwhen they are shared (e.g. combination electrodes). In variousembodiments, the capacitive frame rate is an integer multiple of thedisplay frame rate. In other embodiments, the capacitive frame rate is afractional multiple of the display frame rate. In yet furtherembodiments, the capacitive frame rate may be any fraction or integer ofthe display frame rate.

In one embodiment, the processing system 110 is configured to operatethe hardware of the input device 100 to detect input in the sensingregion-e.g., some portion of the display screen. In the embodimentshown, the processing system 110 includes at least a driver module 220and a receiver module 224 coupled to the plurality of transmitterelectrodes 202 and the plurality of receiver electrodes 204. The drivermodule 220 may include driver circuitry 222 coupled to the transmitterelectrodes 202 and configured to drive the hardware components forcapacitive sensing and for display updating. In some embodiments, thedriver module 220 may be implemented as a capacitive sensing controllermodule communicatively coupled to a separate display driver controller,or as a single controller configured to provide both capacitive sensingand display updating.

In past approaches, when one or more transmitter electrodes are drivenfor capacitive sensing, inactive transmitter electrodes are driven to ashielding level (e.g., ground, V-com) to provide shielding. However, asthe RC time of a capacitive sensor is generally determined by theresistive and capacitive properties of all sensor electrodes involvedduring touch sensing, connecting the inactive transmitter electrodes toa level may increase the total capacitive load of the sensor device.Specifically, the inactive transmitter electrodes driven for shieldingmay be cross-coupled to the receiver electrode by a capacitance 234(i.e., C_(T)) between each intersection of a receiver electrode and atransmitter electrode, thereby increasing the capacitive load of theentire sensor device. As such, as the number of transmitter electrodesin sensor devices increases, for example, due to the sensor devicesthemselves being made in larger sizes, this effect on capacitive loadand the corresponding impact on settling time of the sensor device alsoincreases. Accordingly, embodiments of the present disclosure provide atechnique for shielding in an input device which also reduces thecapacitive load and results in a faster settling time for the capacitivesensor.

In one embodiment, the driver module 220 is configured to drive one ormore transmitter electrodes with a transmitter signal for capacitivesensing, while electrically floating at least one other transmitterelectrode (e.g., connecting to an infinite input impedance). In theembodiment shown in FIG. 2, the driver module 220 includes logic 214,depicted as a set of switches, that determines a state of eachtransmitter electrode 202 as being driven with a transmitter signal oras being electrically floated. For example, the driver module 220 maydrive a first transmitter electrode 202-1, while electrically floatingthe at least one of the other “inactive” transmitter electrodes 202-2,202-3, 202-4, . . . 202-N, as represented by the state of the switchesin logic 214. The set of switches depicted for logic 214 may be externalto the driver module 220 as shown in FIG. 2 (e.g., residing in eithercomponents communicately coupled to the driver module 220 or directly onglass), or in other embodiments, may be internal to driver module 220.

In one embodiment, the receiver module 224 having receiver circuitry 226is coupled to the plurality of receiver electrodes 204. The receivermodule 208 is configured to receive resulting signals from the pluralityof receiver electrodes 204 when performing capacitive sensing within thesensing region 120. In one embodiment, the processing system 110 isfurther configured to determine positional information based onresulting signals. In some embodiments, the processing system 110 may beconfigured to generate an indication of object presence in the sensingregion 120 based on resulting signals received by the receiverelectrodes 204.

According to one embodiment, the input device 100 includes a system 250for updating a plurality of pixels 232 in a display device. In oneembodiment, at least a portion of elements of the plurality of pixels232 may be disposed on a thin-film-transistor (TFT) substrate of thedisplay device. The schematic view of FIG. 2 illustrates a system 250that includes a plurality of source drivers 216 (e.g., 216-1, 216-2, . .. 216-K) coupled to the pixels 232 by a plurality of conductiveelectrodes in the TFT substrate referred to as source lines 206 (e.g.,206-1, 206-1, . . . 206-K). Row select logic (not shown), also referredto as gate selection logic, may select one of the rows of pixels 232 byactivating respective transistor switches 238 in the pixels 232 viaconductive electrodes in the TFT substrate referred to as gate lines210.

When activated, the transistor switches 238 of the pixels 232 enable aconductive path, through the source lines 206, which source drivers 216may drive a desired voltage across the capacitors 230. The voltage ofthe capacitors 230 is defined by the voltage difference between thevoltage on the source lines 206 and a reference voltage (e.g., V-com).In one embodiment, the pixels 232 are coupled to the reference voltage(e.g., V-com) via one or more conductive electrodes referred to as V-comelectrodes 212. In one embodiment, the capacitance of capacitors 230 maybe based on, at least in part, liquid crystal material used to set thecolor associated with the pixels 232. However, the embodiments describedherein are not limited to any particular display technology and may beused, for example, with LED (light emitting diode), OLED (organiclight-emitting diode), CRT (cathode ray tube), plasma, EL(electroluminescent), or other display technology.

The row select logic may raster through the individual rows of thedisplay screen until all the pixels 232 have been updated. For example,row select logic may activate a single row of pixels 232 using anindividual gate line 210. In response, the source drivers 216 may driverespective voltages onto the source lines 206 that generate a desiredvoltage (relative to the reference voltage) across the capacitors 230 inthe selected row of pixels 232. The row select logic may thende-activate the previously selected row of pixels 232 and the sourcedrivers 216 may be controlled, for example, by a display driver moduleon the processing system 110 such that the source drivers 216 providesthe correct voltage for the pixels 232 as the row select logic activateseach row of pixels 232 individually.

The processing system 110 may be configured to actively drive orelectrically float one or more conductive electrodes in a TFT layer of adisplay device to provide shielding while the transmitter electrodes 202are being operated for capacitive sensing. In one embodiment, theprocessing system 110 is configured to drive the plurality of sourcelines 206 with a signal while the transmitter electrodes 202 are beingoperated for capacitive sensing (i.e., one or more transmitterelectrodes 202 are driven with a transmitter signal while the othertransmitter electrodes 202 are electrically floated).

In some embodiments, the signal of the source lines 206 may be asubstantially constant voltage signal (i.e., level) produced by sourcedrivers 216. The source drivers 216 may be output source amplifiers ofthe driver module 220 configured to drive for both display updating andintegrated touch sensing, or in other embodiments, output sourceamplifiers of a separate display driver module communicatively coupledto the driver module 220. In some embodiments, the signal of the sourcelines 206 may be based on the pixel update signal used for displayupdating, i.e., the signal used to generate a desired voltage acrosscapacitors 230 of a pixel 232. In other embodiments, the signal of thesource lines 206 may be produced by multiplexing the source lines 206 toa voltage level. In other embodiments, the signal of the source lines206 may be a varying voltage signal (e.g., related to the transmittersignal driven on the transmitter electrodes). In another embodiment, thesource lines 206 may be coupled to source line logic 218, depicted inFIG. 2 as a set of switches, configured to determine a state of thesource lines between electrically floated and actively driven fordisplay updating. The set of switches depicted for source line logic 218may be external to the driver module 220 as shown in FIG. 2 (e.g.,residing in either components communicately coupled to the driver module220 or directly on glass), or in other embodiments, may be internal todriver module 220.

According to one embodiment, the pixels 232 may be separated from theplurality of transmitter electrodes 202 and receiver electrodes 204 byone or more insulated layers. In other embodiments, the sensorelectrodes (i.e., the transmitter electrodes 202, the receiverelectrodes 204) may be shared in functionality with display electrodesof the pixels 232, an example of which is illustrated in FIG. 3.

FIG. 3 illustrates an alternative embodiment of the input deviceconfigured to shield with display elements. FIG. 3 illustrates a system300 where the conductive electrodes used to carry the reference voltage(e.g., V-com) are also used to carry the transmitter signals forcapacitive sensing. Each transmitter electrode 202 (e.g., 202-1, 202-i,. . . 202-N) shown in system 300 represents one or more of theconductive electrodes (e.g., V-com electrodes 212) used to apply thereference voltage to one side of the capacitors 230 during displayupdating, which may further be used to transmit a modulated electricalsignal 302 during capacitive sensing. In one embodiment, the transmitterelectrodes 202 may be coupled to the driver module 220 for generatingthe transmitter signal on the common electrodes 212. In otherembodiments, the driver module 220 may be coupled to the commonelectrodes of the transmitter electrodes via intermediate logic (notshown), such as row select logic. When updating the display, row selectlogic may be used to couple different common electrodes 212 to thereference voltage (e.g., V-com). As row select logic and source drivers216 update the voltages stored in the pixels 232, the transmitter signaloutput of driver module 220 may be inactive (e.g., have high or infiniteinput impedance).

In some embodiments, the system 300 includes separate logic referred toherein as transmitter select logic, which is configured to select atransmitter electrode to drive and, in some embodiments, whichtransmitter electrode(s) to electrically float. In some embodiments, thesystem 300 may include high-level logic that includes both row selectlogic and transmitter select logic. A driver module 220 may be coupledto the transmitter electrodes 202 through the high-level logic or may bedirectly coupled to the transmitter electrodes 202.

In some embodiments, rather than be separate, the driver module 220includes at least one of the row select logic and the transmitter selectlogic. In such an embodiment, instead of driving a varying voltage ontoeach transmitter electrode, two voltages may be selectively connected toa transmitter electrode to modulate the transmitter electrode betweenthose two voltages. In one embodiment, at least one of the voltagesselectively connected may be a reference voltage (e.g., V-com). In otherembodiments, at least one of the voltages selectively connected may be ahigh and low transmitter signal.

In one embodiment, logic switches may be opened and closed toelectrically float sets of common electrodes corresponding totransmitter electrodes 202 during capacitive sensing. For example, whenperforming capacitive sensing, as discussed above, one of the logicswitches described earlier may be closed to allow the driver module 220to drive a transmitter signal on the set of common electrodescorresponding to a first transmitter electrode 202-1. Further, whilecommon electrodes corresponding to a first transmitter electrode 202-1are being driven with transmitter signal, another logic switch may beopened to electrically float the inactive sets of common electrodescorresponding to other transmitter electrodes 202-i to 202-N, and thesource lines 206 may be actively driven to a level by source drivers216.

Although FIG. 3 illustrates connecting one row (e.g., one commonelectrode 212) to driver module 220, multiple common electrodes 212 maybe combined or grouped into a transmitter electrode that is driven bythe driver module 220. In some embodiments, the receiver electrodes 204may be dedicated sensor electrodes for capacitive sensing, as shown inFIG. 2, or, in other embodiments, it may be desirable to use one or moreelectrodes in the system 300 for receiving resulting signals whencapacitive sensing, such as the electrodes that carry the referencevoltage.

FIG. 4 is a flow diagram illustrating a method 400 for operating aninput device having an associated display device, according to oneembodiment of the disclosure. In the embodiment shown, at step 402, theprocessing system 110 of the input device 100 drives one or moretransmitter electrodes 202 with a transmitter signal. While driving thetransmitter electrode(s) 202, at step 404, the processing system 110electrically floats a second transmitter electrode. In some embodiments,the second transmitter electrode may include those inactive transmitterelectrodes not being driven with the transmitter signal.

Further while driving the transmitter electrodes 202 with thetransmitter signal, the processing system 110 may operate at least oneof the conductive electrodes in the TFT layer of the display device forshielding. In some embodiments, the conductive electrodes operated maybe the plurality of source lines 206 found in the TFT layer of thedisplay device. In other embodiments, the conductive electrodes operatedmay be the plurality of gate lines 210 found in the TFT layer of thedisplay device, or may be any combination of source lines 206 and gatelines 210 found in the TFT layer of the display device.

In one embodiment, the processing system may operate the conductiveelectrodes in the TFT layer of the display device to shield againstinterference by, at step 406, driving at least one of the plurality ofconductive electrodes with a first signal. In some embodiments, thefirst signal may be a substantially constant voltage signal. In otherembodiments, the first signal may be a varying voltage signal. In someembodiments, the first signal may be a waveform based, at least in part,on the same transmitter signal used to drive the transmitter electrodes.For example, the first signal may be a “guard” signal being at leastsubstantially similar to the transmitter signal used to drive thetransmitter electrodes (e.g., similar frequency, similar amplitude,and/or similar phase). In another example, the first signal may have awaveform opposite relative the transmitter signal used to drive thetransmitter electrodes. In other embodiments, where the conductiveelectrodes in the TFT layer may have been previously driven with a pixelupdate signal for display updating, the first signal may be based, atleast in part, on the same pixel update signal.

In another embodiment, the processing system may operate the conductiveelectrodes in the TFT layer of the display device to shield againstinterference by, at step 408, electrically floating at least one of theplurality of conductive electrodes.

At step 410, the receiver module of the processing system receives aresulting signal from at least one of the receiver electrodes. Theprocessing system 110 may generate an indication of an object presencein the sensing region 120 based on the resulting signal.

While embodiments described herein utilize the source lines of the TFTlayer to shield against interference during capacitive sensing, in someembodiments, it may be desired to use the plurality of gate lines of theTFT layer, instead of or in conjunction with the source lines, to shieldagainst interference. In such an embodiment, the plurality of gate lines210 can be held at level (e.g., high or low voltages) while performingtouch sensing to provide shielding.

In one embodiment, the conductive electrodes of the TFT layer used toshield against interference may be determined based on an orientation ofthe receiver electrodes of the input device. In the embodiment shown inFIG. 2, the plurality of source lines 206 of the display device may beused for shielding because the source lines 206 have an orientation thatis aligned with the plurality of receiver electrodes 204. In otherembodiments, for example, in input devices having a “landscape”configuration where the receiver electrodes may be oriented horizontallyalong the width of the input device, the plurality of gate lines 210 maybe used for shielding because the gate lines 210 are aligned in the samedirection as the receiver electrodes.

Accordingly, embodiments of the present disclosure provide a techniquefor shielding while performing touch sensing that achieves fastersettling of touch sensors than previous approaches. Inactive transmitterelectrodes are floated, thereby reducing the capacitive load of thetouch sensor, yet shielding effects are still achieved by driving thedisplay source lines to a level or electrically floating the displaysource lines. It should be appreciated that the faster settling for thetouch sensor enables better mitigation of interference, as the fastersettling allows the touch sensor to be driven with higher frequenciesand have more touch samples filtered per transmission. From atime-budget perspective, the amount of time available to perform touchsensing can be greatly reduced in larger displays (e.g., as measured indiagonal sizes) and/or higher resolution displays. As such, the fastersettling allows the touch sensor to capture the needed amount of touchsamples in a shorter amount of time.

While the foregoing is directed to embodiments of the presentdisclosure, other and further embodiments of the disclosure may bedevised without departing from the basic scope thereof, and the scopethereof is determined by the claims that follow.

The invention claimed is:
 1. A processing system for a display devicehaving an integrated capacitive sensing device, the processing systemconfigured to couple to a plurality of sensor electrodes and a pluralityof conductive electrodes of the display device, the processing systemfurther configured to: drive a first sensor electrode of the pluralityof sensor electrodes with a first signal for capacitive sensing; whiledriving the first sensor electrode of the plurality of sensor electrodeswith the first signal for capacitive sensing, drive at least oneconductive electrode of the plurality of conductive electrodes with aguard signal, wherein the guard signal comprises a varying voltagesignal and is similar to the first signal, wherein each of the pluralityof sensor electrodes comprises at least one common electrode of aplurality of common electrodes of the display device, wherein theplurality of common electrodes are driven for display updating andcapacitive sensing, and wherein the at least one conductive electrode ofthe plurality of conductive electrodes comprises one of a source line ora gate line; and while driving the at least one conductive electrode ofthe plurality of conductive electrodes with the guard signal,electrically float at least one other conductive electrode of theplurality of conductive electrodes, wherein the at least one otherconductive electrode of the plurality of conductive electrodes comprisesthe other one of the source line or the gate line.
 2. The processingsystem of claim 1, wherein driving the first sensor electrode with thefirst signal for capacitive sensing comprises driving the first sensorelectrode to detect changes in absolute capacitance.
 3. The processingsystem of claim 1, wherein the first signal comprises a transmittersignal, wherein the processing system is further configured to receiveresulting signals with a receiver, and wherein the resulting signalscomprise effects corresponding to the transmitter signal.
 4. Theprocessing system of claim 3, wherein while the first sensor electrodeis driven with the transmitter signal for capacitive sensing, a secondsensor electrode of the plurality of sensor electrodes is electricallyfloated.
 5. The processing system of claim 1, wherein the at least oneconductive electrode of the plurality of conductive electrodes comprisesa source line, and wherein the at least one other conductive electrodeof the plurality of conductive electrodes comprises a gate line.
 6. Theprocessing system of claim 1, wherein the at least one conductiveelectrode of the plurality of conductive electrodes comprises a gateline, and wherein the at least one other conductive electrode of theplurality conductive electrodes comprises a source line.
 7. Theprocessing system of claim 1, wherein the varying voltage signal and thefirst signal comprise at least one of: a similar frequency, a similaramplitude, or a similar phrase.
 8. An input device comprising: aplurality of sensor electrodes, wherein each of the plurality of sensorelectrodes comprises at least one common electrode of a plurality ofcommon electrodes of the input device, and wherein the plurality ofcommon electrodes are driven for display updating and capacitivesensing; a plurality of conductive electrodes of the input device; and aprocessing system configured to couple to the plurality of sensorelectrodes and the plurality of conductive electrodes, wherein theprocessing system is further configured to: drive a first sensorelectrode of the plurality of sensor electrodes with a first signal forcapacitive sensing; while driving the first sensor electrode of theplurality of sensor electrodes with the first signal for capacitivesensing, drive at least one of the plurality of conductive electrodeswith a guard signal, wherein the guard signal comprises a varyingvoltage signal and is similar to the first signal, and wherein the atleast one conductive electrode of the plurality of conductive electrodescomprises one of a source line or a gate line; and while driving the atleast one conductive electrode of the plurality of conductive electrodeswith the guard signal, electrically float at least one other conductiveelectrode of the plurality of conductive electrodes, wherein the atleast one other conductive electrode of the plurality of conductiveelectrodes comprises the other one of the source line or the gate line.9. The input device of claim 8, wherein the plurality of sensorelectrodes are disposed in a matrix array of rectangles of a same sizeand shape.
 10. The input device of claim 8, wherein driving the firstsensor electrode with the first signal for capacitive sensing comprisesdriving the first sensor electrode to detect changes in absolutecapacitance.
 11. The input device of claim 8, wherein the first signalcomprises a transmitter signal, wherein the processing system is furtherconfigured to receive resulting signals with a receiver electrode, andwherein the resulting signals comprise effects corresponding to thetransmitter signal.
 12. The input device of claim 11, wherein while thefirst sensor electrode is driven with the transmitter signal forcapacitive sensing, a second sensor electrode of the plurality of sensorelectrodes is electrically floated.
 13. The input device of claim 11,wherein the receiver electrode comprises at least one common electrodeof the plurality of common electrodes.
 14. The input device of claim 11,wherein the receiver electrode and the plurality of sensor electrodesare disposed on different layers within the input device.
 15. The inputdevice of claim 8, wherein the at least one conductive electrode of theplurality of conductive electrodes comprises a source line, and whereinthe at least one other conductive electrode of the plurality ofconductive electrodes comprises a gate line.
 16. The input device ofclaim 8, wherein the at least one conductive electrode of the pluralityof conductive electrodes comprises a gate line, and wherein the at leastone other conductive electrode of the plurality conductive electrodescomprises a source line.
 17. The input device of claim 8, wherein thevarying voltage signal and the first signal comprise at least one of: asimilar frequency, a similar amplitude, or a similar phrase.
 18. Amethod for operating a display device having an integrated capacitivesensing device, the method comprising: driving a first sensor electrodeof a plurality of sensor electrodes with a first signal for capacitivesensing, wherein each of the plurality of sensor electrodes comprises atleast one common electrode of a plurality of common electrodes of thedisplay device, and wherein the plurality of common electrodes aredriven for display updating and capacitive sensing; while driving thefirst sensor electrode of the plurality of sensor electrodes with thefirst signal for capacitive sensing, driving at least one conductiveelectrode of a plurality of conductive electrodes with a guard signal,wherein the guard signal comprises a varying voltage signal and issimilar to the first signal, and wherein the at least one conductiveelectrode of the plurality of conductive electrodes comprises one of asource line or a gate line; and while driving the at least oneconductive electrode of the plurality of conductive electrodes with theguard signal, electrically floating at least one other conductiveelectrode of the plurality of conductive electrodes, wherein the atleast one other conductive electrode of the plurality of conductiveelectrodes comprises the other one of the source line or the gate line.19. The method system of claim 18, wherein driving the first sensorelectrode with the first signal for capacitive sensing comprises drivingthe first sensor electrode to detect changes in absolute capacitance.20. The method system of claim 18, wherein the first signal comprises atransmitter signal, wherein the method further comprises receivingresulting signals with a receiver electrode, wherein the resultingsignals comprise effects corresponding to the transmitter signal, andwherein while the first sensor electrode is driven for capacitivesensing, a second sensor electrode of the plurality of sensor electrodesis electrically floated.